There are many applications for which precise control over the amount and/or rate at which a fluid is dispensed by a pumping apparatus is necessary. In semiconductor processing, for example, it is important to control the amount and rate at which photochemicals, such as photoresist chemicals, are applied to a semiconductor wafer. The coatings applied to semiconductor wafers during processing typically require a certain flatness and/or even thickness across the surface of the wafer that is measured in angstroms. The rates at which processing chemicals are applied (i.e., dispensed) onto the wafer have to be controlled carefully to ensure that the processing liquid is applied uniformly.
Photochemicals used in the semiconductor industry today are typically very expensive, costing as much as $1000 and up per a liter. Therefore, it is highly desirable to ensure that a minimum but adequate amount of chemical is used and that the chemical is not damaged by the pumping apparatus.
Unfortunately, these desirable qualities can be extremely difficult to achieve in today's pumping systems because of the many interrelated obstacles. For instance, an o-ring is often needed in a fitting assembly to improve the seal of a filter or fluid connection, between a surface of the fitting and a receiving surface of a block to which the fitting is attached. O-rings generally deteriorate over a period of time, causing the fitting assembly to become leaky, wasting precious fluid and causing undesirable pressure changes. Such pressure changes may be damaging to the fluid (i.e., may change the physical characteristics of the fluid unfavorably) and/or adversely affect the performance of the pumping system.
Moreover, previously developed fittings and fitting assemblies tend to be bulky and therefore are not suitable to be used in pumps with a small footprint and height limitation. There is a need for an o-ring-less low profile fitting and fitting assembly for filter and fluid connections in a fluid pump.
Embodiments of the invention can address these needs and more.